Quantitative analysis of primaquine and its metabolites in human urine using liquid chromatography coupled with tandem mass spectrometry

Primaquine (PQ), a prototype 8-aminoquinoline (8-AQ) drug used to treat malaria, is rapidly metabolized into different inactive and active metabolites. Due to the hemolytic toxicity, the uses of PQ have been confined. To understand its overall metabolism and its relation to drug efficacy and toxicity, profiling of urine for the parent drug and its metabolites is important. The current study presents a convenient and rapid method for simulta-neously quantifying primaquine (PQ) and its metabolites in human urine. A simple liquid-liquid extraction followed by chromatographic separation and quantification through ultra-performance liquid chromatography -tandem mass spectrometry (UPLC-MS/MS) was developed and validated to quantify PQ and its eleven metab-olites in the urine of healthy human volunteers who received a single oral dose of PQ. The developed method separated fourteen analytes, including internal standards, within nine minutes of run time. The linearity of all analytes was suitable in the range of 1-500 ng/mL. The extraction recovery for all concentrations of analytes from urine was ranged from 90.1 to 112.9 %. The relative standard deviation for intra-and inter-day precision were < 9.8 and < 10.7 %, respectively. Along with PQ, its different metabolites were detected in urine. Primaquine-5,6-orthoquinone, the N-carbamoylglucuronide conjugate of PQ and carboxyprimaquine were the major metabolites found in urine. Significant enantiomeric differences in the urinary excretion profiles for PQ and metabolites were observed. This analytical method can be implemented in the pharmacokinetic analysis of PQ to explain its toxicity and clinical decision making.

Automated summary

A convenient and rapid method for simultaneously quantifying primaquine (PQ) and its metabolites in human urine was developed and validated. The method showed good linearity, extraction recovery, and precision, and can be used in pharmacokinetic analysis of PQ to explain its toxicity and clinical decision making.